Hi guys, I've been thru so many threads trying to nail down the high idle problem on my 1985 300zx NA, I'd figured I'd come here and hope you guys can help me out!!
I'm sorry if this is going to be a lot of text, I just want to give out every detail I can and hope I can finally get this car running like 1985 again- It's 5 speed and digital package if that matters-
I've had the car for many months now, and it's always had a high idle (Currently around 1100 RPM/ 1300 with lights on) and has been hard to start cold (Would always crank and crank and finally sputter into life). I'd have to let the car warm up before trying to drive it or else it feels like it's firing on half it's cylinders and missing. After the engine actually starts it'll run, then the idle drops to about 900, sometimes the normal 700 or 800, but like I said you can't drive it while it does this. Eventually the idle will jump back up to the high 1100 or up to 1400 at times and then it'll finally drive, but with definitely less power than it should have.
Yesterday was the first time in about 3-4 days I started the car up, and it actually fired right up- but then went into a fit with the idle dropping as low as 500/600 and the engine struggling for life. Revving it you could hear missing. After 10-20 minutes it finally picked the idle back up and would drive, with not much power but it'd drive.
Since owning the car I've done just about everything all the forums say- CHTS and harness was replaced and reads within 2k-3k ohms like it should, every vacuum line (even way back above the fuel tank for the EVAP) has been inspected and/or replaced. I did spark plugs and wires (Gapped to 0.40). I spent today making sure all the plug wires are firing, disassembled and cleaned the Idle Air Control, and replaced any even REMOTELY sketchy-looking vacuum lines. Still 1100 RPM.
I have checked the ECM for codes before and they were 23 (Throttle Valve Switch (IDLE SWITCH) circuit) and 31 Load signal circuit (Think it only throws that because the A/C needs recharge).
I'm only seeing so many options left, but I'd really appreciate any input you guys can give me. All I know left to do is replace the IAC or fault the ECM. Looking back on code 23 I'm leaning towards the IAC is dead, but it's weird how it still raises the idle 200 RPM just like it should when you flip the lights on? Has anybody else had high idle trouble and what was the cause?
Thank you so much for reading / any ideas guys!!
I'm sorry if this is going to be a lot of text, I just want to give out every detail I can and hope I can finally get this car running like 1985 again- It's 5 speed and digital package if that matters-
I've had the car for many months now, and it's always had a high idle (Currently around 1100 RPM/ 1300 with lights on) and has been hard to start cold (Would always crank and crank and finally sputter into life). I'd have to let the car warm up before trying to drive it or else it feels like it's firing on half it's cylinders and missing. After the engine actually starts it'll run, then the idle drops to about 900, sometimes the normal 700 or 800, but like I said you can't drive it while it does this. Eventually the idle will jump back up to the high 1100 or up to 1400 at times and then it'll finally drive, but with definitely less power than it should have.
Yesterday was the first time in about 3-4 days I started the car up, and it actually fired right up- but then went into a fit with the idle dropping as low as 500/600 and the engine struggling for life. Revving it you could hear missing. After 10-20 minutes it finally picked the idle back up and would drive, with not much power but it'd drive.
Since owning the car I've done just about everything all the forums say- CHTS and harness was replaced and reads within 2k-3k ohms like it should, every vacuum line (even way back above the fuel tank for the EVAP) has been inspected and/or replaced. I did spark plugs and wires (Gapped to 0.40). I spent today making sure all the plug wires are firing, disassembled and cleaned the Idle Air Control, and replaced any even REMOTELY sketchy-looking vacuum lines. Still 1100 RPM.
I have checked the ECM for codes before and they were 23 (Throttle Valve Switch (IDLE SWITCH) circuit) and 31 Load signal circuit (Think it only throws that because the A/C needs recharge).
I'm only seeing so many options left, but I'd really appreciate any input you guys can give me. All I know left to do is replace the IAC or fault the ECM. Looking back on code 23 I'm leaning towards the IAC is dead, but it's weird how it still raises the idle 200 RPM just like it should when you flip the lights on? Has anybody else had high idle trouble and what was the cause?
Thank you so much for reading / any ideas guys!!
Comment